114 CHEMICAL COMPOSITION OF ANIMAL TISSUES. 



development : and the varying proportions in which it presents itself 

 there, are evidently closely connected with the formative powers of that 

 fluid. It is also a principal element of certain colourless exudations, 

 which are put forth from wounded or inflamed surfaces, or which are 

 deposited in the interstices of inflamed tissues ; these exudations, when 

 possessed of a high formative property (that is, a readiness to produce 

 an organized tissue), are said to be composed of coaguldble or organi- 

 zable lymph, which is nothing more than the fibrinous element of the 

 blood, in an unusually concentrated state. We shall first notice the 

 Chemical properties of Fibrine ; and shall then inquire into those, which 

 present the first dawnings or indications of Vitality. 



179. Like the other Proteine-compounds, Fibrine may exist in 

 solution, or in an insoluble form ; but there is this important dif- 

 ference, that its soluble form is not a permanent one, and can- 

 not be maintained in any fibrinous fluid that has been drawn from the 

 living vessels, without the influence of reagents, which totally destroy 

 its peculiar properties. All investigations of a Chemical nature, there- 

 fore, must be made upon insoluble Fibrine ; and this may be obtained in 

 its purest state, by whipping fresh blood with a bundle of twigs, by 

 which operation it will be caused, in coagulating, to adhere to the twigs 

 in the form of long, white, elastic filaments, with scarcely an admixture 

 of foreign matter. When dried in vacuo, or at a gentle heat, it becomes 

 translucent and horny ; and in this condition, it closely resembles coagu- 

 lated albumen. It further resembles that substance, in being soluble in 

 very dilute caustic alkali, and in phosphoric acid ; and the solutions 

 exhibit many of the properties of the similar solutions of albumen. 

 When the Fibrine of venous blood is triturated in a mortar with a solu- 

 tion of nitrate of, potash, and the mixture is left for twenty-four hours 

 or more, at a temperature of from 100 to 120, it becomes gelatinous, 

 slimy, and eventually entirely liquid. In this condition, it exhibits all 

 the properties of a solution of Albumen which has been neutralized by 

 acetic acid. It coagulates by heat ; it is precipitated by alcohol, corro- 

 sive sublimate, &c.; and, when largely diluted, it deposits a flocculent 

 substance, not to be distinguished from insoluble albumen. The close 

 Chemical relation of Fibrine and Albumen is further proved by the ready 

 conversion of the former into the latter in the act of digestion ; Animal 

 flesh, which consists of Fibrine, being reduced to the form of Albumen 

 with the same facility, as the Vegetable compounds which resemble the 

 latter much more closely in the first instance. The Fibrine of arterial 

 blood, however, cannot be reduced to the fluid form by solution with 

 nitre ; and this appears to be due to its oxidized condition ; for in a solu- 

 tion of Venous fibrine in nitre, contained in a deep cylindrical jar, and 

 having its surface freely exposed to the air, a fine flocculent precipitate 

 is gradually seen to form ; and this, when collected, is found to have the 

 properties of arterial fibrine. The Fibrine of Animal flesh agrees with 

 that of venous, rather than with that of arterial blood. Fibrine, like 

 Albumen, unites with acids as a base, forming definite compounds ; and 

 with bases as an acid. It also possesses the property of uniting with 

 the earthy phosphates ; of which from 0-7 to 2-5 per cent, are found in 

 the ash that is left after its combustion. 



